Nexus 6: b9-t3 / b3-t3-M

I've merged a lot wi-fi stuff from the google repo, added some mainline updates for nohz and finally merged the m-preview 2 source. Toolchain also got updated.

Changelog:
-wi-fi updates
-nohz updates
-m-prev2 source
-toolchain updated

Refer to -t4

Have fun! (=

hells